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No. 372,409. Patented Nov. 1, 1887.

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W. FISCHER & T. STIEHL.

DRAFT REGULATOR FOR FURNACES.

Patented Nov. 1, 1887.

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UNITED STATES PATENT OFFICE.

\VILHELM FISCHER AND THEODOR STIEHL, OF ESSEN-ON-THERUHR, PRUSSIA, GERMANY.

DRAFT-REGULATOR FOR FURNACES.

sPECIFICATION zorming part of Letters Patent No. 372,409, dated November 1, 1887.

(No model.)

To all whom, it may concern:

Be it known that we, \VILHELM FISCHER and THEoDoR STIEHL, both subjects of the King of Prussia, German Empire, and residents of Essen-011 the-Ruhr, in the Kingdom of Prussia,Empire of Germany, have invented certain new and usefulImprovements in Regulators for Temperature for Furnaces, of which the following is a specification.

Our invention relates to improvements in regulators for temperature for furnaces, the purpose of which is to shut off the combustion air led to the grate as soon as the temperature of the body heated by the furnace has reached or gone beyond a certain height. The body heated by the furnace may be a steam-boiler for generating steam to drive a steam-engine, or it may be the boiler of an apparatus for heating by means of hot water or steam. The body thus heated may even be a stove for heating the air in compartmentsin which case the temperature of the air in them, on reaching a certain heigl1t,prevents automatically the further admittance of combustion air to the grate. As soon as the temperature produced by shutting off the air from the furnace begins to fall, the regulator admits the air to the furnace again by means of a self-acting contrivance. The temperature of the boiler, or the heating apparatus, or the stove, with whichsoever the apparatus hereinafter described may be connected, keeps this temperature up at a normal height. Of course it is presumed that the fire is large enough to produce the temperature required.

The apparatus is represented in Figures I and II. Fig. I shows a section, M N, through the apparatus; and Fig. ll illustrates a section, 0 P, likewise through the apparatus.

The apparatus consists of a pipe, 1). One end, f, of the latter leads under the grate of the furnace the heating effect of which has to be regulated. The furnace is otherwise shut off from the air on all sides. Air can only penetrate to the furnace through pipe 19 and through the open end 1) of the latter. The

pipe end 1; is covered with an elastic plate, 1", which is best made of india-rubber, in such a way that this plate or cap 1" can both be lifted and made to lie tight over the opening of pipe 11. The plate 1' is attached to a plate, t. The bearing-arm t of the latter is provided with openings 8, so that the air can enter and penetrate to the annular space 8, which surrounds the pipe cnd p and is limited by the plate t. The elastic plate r is covered with a cap, k, in such a way that a closed space, at, is left between the cap is and the plate 1. This space at can be connected with an airsuction mechanism, 0, forinstance a chimney. Space :6 can also be shut off from the chimney and brought into connection with the atmospheric air. This is effected, as shown in the drawings, by means of the arrangements and mech anisms hereinafter described.

A pipe, k, coming from the small cylinder 11, terminates in the closed space so. The cylinder a is provided with openings 0 and a small piston, e, which is suspended to the rod e, working in it. This rod 0 is fastened to the oscillating lever d b, the one end of which forms an anchor or armature, Z), for an electromagnet, 0.. An electric current can be produced round the magnet a by means of a galvanic element, g, which is represented in Fig. ll of the accompanying drawings. The current being closed, the anchor or armature I) is drawn down toward the magnet a, and consequently the arm (Z raises the piston c in the cylinder u. A mercurial thermometer is attached to the conducting-wires ff in such a Way that one of these wires, 1, is in constant connection with the mercury of the theri'nometer. The other wire, f, leads to a platina wire attached to the mercurial tube. This platina wire is attached at a height in the mercurial tube correspond ing with temperature which is not to be eX- ceeded. This thermometer is exposed to the temperature of the space to be regulated, no matter whether it be a steam-boiler, an airspace, or a vessel for heating by means of hot water.

The apparatnsj ust described,and from which the wiresff lead on the one hand to the thermometer h and on the other hand to the ele* ment 9, is closed hermetically by a metal cover, 5. It is still to be mentioned that two channels are made in the cover-plate k of the space m. One of these channels, m, connects the interior, I, of the metal cap i with the chimney- IOO pipe 0, and the other channel, Z, connects the atmospheric air with the space z, which is located under the piston e. \Vadding is laid between the sieves z z" of the space 2, to prevent the dust getting in cylinder to.

The way in which the apparatus works is as follows: The airin the space Iis constantly thinned or rarefied by the chimney-pipe 0. If the piston c of the lever d b is under the openings 0 of the cylinder at, then the rarefying of the air will also take place in pipe k and in space as. The elastic plate 1" will be sucked upward thereby and come into the position shown in Fig. I. The air then passes through the annular space 8 to the pipe pp p and through the latter under the tire-grate. As soon as the fire begins to heat the steam-boiler, or the room, or the water-reservoir too much, the thermometer will rise and reach the highest point indicated by the platina wire f". The electric circuit is then closed, and the ap paratus begins to operate, the anchor or armature b is attracted by the electro-magnet a,

and the piston e rises above the openings 0 in the cylinder 10. The pipe and with it space 00, is then shutoff from the space I, which contains rarefied air, and space 00 comes in connection with the atmospheric air by means of channel 70, space 2, and channel Z. The rarefying of the air, which raises the plate '1", then ceases, and plate r, depressed by its own weight and by the draft in pipe pp, falls on the pipe end 1) and closes it. As the combustion air is then shut off from the fire, the latter gradually declines till the mercury in the thermometer has fallen below the platina wire, and the circuit is interrupted again. The electro-magnet releases its hold of the anchor b, the piston e of the long lever-arm (1 falls, owing to the overweight of the lever arm 01 over the shorter arm b, and the elastic plate 1' is raised again by the entrance of the rarefied air from the space I.

It is a matter of course that instead of the electrical openingand closing other automatical contrivances can be used for the purpose of admitting and shutting off the rarefied air of the chimney. Our invention relates not only to this method of opening and closing, but also to the general arrangement of the air-inlet pipe with the elastic plate 7*, without which, in fact, an automatic opening and closing is not possible.

For the purpose of regulating the temperature simultaneously in more than one room by means of this apparatus, several thermometers located in such rooms can be connected with the conducting-wires. These thermometers may form together one branch of the electric circuit, as shown in Fig. II, by the thermometers I and II, or they may be placed parallel to each other, as shown inFig. II by dotted lines, (thermometers III and IV.) When arranged as first described, an equality of temperature must prevail in all the spaces (thermometers) before the electric circuit is closed; but when the thermometers are placed parallel to one another the electric circuit is closed whenever the temperature has reached in one of the spaces the point not to be exceeded.

What we claim, and desire to secure by Letters Patent of the United States, is-

1. A regulating and shuttingofi" contrivauce for air led to a firegrate, consisting of the air-inlet channel pp, the elastic plate 7", arranged before the latter, the air inlet opening 8, the cap 70, the closed space 00, which is left between plate 1" and cap 7c, and in the chimney.

withwhich the closed spacem' may be brought in connection, or from which it may be shut off, substantially as set forth, and for the pur-. pose specified.

2. A regulating and shutting-off contriv- In witness whereof we have hereunto set our hands in presence of two witnesses.

WILHELM FISCHER. THEODOR STIEHL.

Witnesses:

HEINRICH LIPPERT, HERMANN KUHFUS. 

